improbability

as a pig loves marjoram Not at all. This now rarely heard emphatic rejoinder derives from the maxim of the Roman poet Lucretius: Amaricinum fugitatsus ‘swine shun marjoram.’

Chinaman’s chance No chance at all; little or no prospect of gaining, achieving, or reaching one’s immediate goal; the near certainty of being thwarted. It is assumed that the phrase derives from the days of the California gold rush (1849) when the Chinese immigrants were victims of discrimination and ill-treatment. Minorities, specifically the Chinese, were denied the opportunity of “striking it rich” and partaking of the “American Dream.”

dark horse An unlikely winner, a long shot; an unfamiliar or unexpected candidate for political office; a person whose abilities and potential are unknown. The term originally referred to a horse whose ability and promise were kept secret until the day of the race. The evolution of the phrase’s figurative meaning in American politics is obvious. A political candidate whose nomination is the result of a compromise is often called a dark horse.

in a pig’s eye No way, not on your life, fat chance. The phrase carries the conviction of absolute certainty, in the negative sense; it is often spoken with a degree of disgust or contentiousness, in response to another’s expression of optimism or likelihood. No origin or explanation of this frequently used phrase has been found. A remote possibility is that it relates to a once popular shipboard game “placing the pig’s eye,” in which the figure of a pig was outlined on the deck, and blindfolded passengers or crew had to place an object representative of a pig’s eye in the proper anatomical position. Their chances of success were slim at best.

a snowball’s chance in hell No chance at all, absolutely no possibility; also, a snow flake’s chance in hell; usually in the phrase as much chance as a snowball in hell. This self-evident American slang expression has been in use since 1931.